The complete amino acid sequences of the anti-tumor lectins ricin, abrin and momordin, purified from the higher plants Ricinus communis (castor bean), Abrus precatorius (jequirity bean) and Momordica charantia (pear melon), respectively, will be determined. The sequences of purified lectin components and peptides derived from chemical and enzymatic cleavages will be determined with an automatic Beckman sequencer. Such fragments will also be examined for specific cell binding or anti-tumor activity. The established primary structures will be used in comparative analysis with three dimensional structural studies that are being carried out in other laboratories to precisely define structure-function correlates in these molecules. A specific longer range goal is to provide a structural basis for the specific synthesis of active components observed in these molecules.